Re: [PATCH] iio: buffer-dmaengine: adjust `bytes_used` with residue info

[Alexandru Ardelean <ardeleanalex@gmail.com>]

On Wed, Aug 26, 2020 at 8:22 AM Lars-Peter Clausen <lars@metafoo.de> wrote:
>
> From: Alexandru Ardelean <alexandru.ardelean@analog.com>
>
> A transfer may fall shorter than the bytes in the block.
> This information is available in the residue from the DMA engine, so we can
> compute actual `bytes_used` with that by subtracting the residue.
>

This was in my pipeline as well [obviously].
Thanks :)

> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
> ---
>  drivers/iio/buffer/industrialio-buffer-dmaengine.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/buffer/industrialio-buffer-dmaengine.c b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
> index 6dedf12b69a4..5789bda0745b 100644
> --- a/drivers/iio/buffer/industrialio-buffer-dmaengine.c
> +++ b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
> @@ -45,7 +45,8 @@ static struct dmaengine_buffer *iio_buffer_to_dmaengine_buffer(
>         return container_of(buffer, struct dmaengine_buffer, queue.buffer);
>  }
>
> -static void iio_dmaengine_buffer_block_done(void *data)
> +static void iio_dmaengine_buffer_block_done(void *data,
> +               const struct dmaengine_result *result)
>  {
>         struct iio_dma_buffer_block *block = data;
>         unsigned long flags;
> @@ -53,6 +54,7 @@ static void iio_dmaengine_buffer_block_done(void *data)
>         spin_lock_irqsave(&block->queue->list_lock, flags);
>         list_del(&block->head);
>         spin_unlock_irqrestore(&block->queue->list_lock, flags);
> +       block->bytes_used -= result->residue;
>         iio_dma_buffer_block_done(block);
>  }
>
> @@ -74,7 +76,7 @@ static int iio_dmaengine_buffer_submit_block(struct iio_dma_buffer_queue *queue,
>         if (!desc)
>                 return -ENOMEM;
>
> -       desc->callback = iio_dmaengine_buffer_block_done;
> +       desc->callback_result = iio_dmaengine_buffer_block_done;
>         desc->callback_param = block;
>
>         cookie = dmaengine_submit(desc);
> --
> 2.20.1
>